Integrated circuits (ICs) are made up of a plurality of interconnected transistors and other components. Complex ICs require several levels of metallization to properly interconnect all of the devices to power the devices, convey input and output signals, address and timing signals, and the like. The several levels of metallization are separated by layers of dielectric material (inter layer dielectric or ILD). Openings are selectively etched through the various ILD layers and those openings are filled with metal or other conductive material to route the signals between devices as needed to implement the desired circuit function.
As the complexity of ICs increases, the number of devices increases, the number of necessary interconnections increases, and the size of individual devices shrinks. Each generation of integrated circuits is characterized by a minimum feature size; that is the minimum line width or the minimum spacing between lines that is used in designing the individual devices. The reduction in feature size is not generally accompanied by a corresponding reduction in the thickness of layers used to fabricate the IC such as the thickness of metal layers, polycrystalline silicon layers, and ILD layers. Accordingly, the cross sectional area of the openings etched through ILD layers decreases more rapidly than the depth of the opening. The aspect ratio, the ratio of opening width to opening depth, thus increases as the IC size and complexity increases. High aspect ratio openings are difficult to reliably etch and fill with metal or other conductive material, leading to reliability issues and increased manufacturing cost.
Accordingly, it is desirable to provide reliable methods for manufacturing complex integrated circuits. In addition, it is desirable to provide self aligned methods for fabricating ICs with reduced aspect ratio contact openings. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.